It is known that dispersibility of a silicone rubber powder in coating materials, cosmetic materials, ink, thermosetting organic resins, thermoplastic organic resins, etc., can be improved by using a composite silicone rubber powder obtained by coating the surface of a conventional silicone rubber powder with a microfine inorganic powder. For example, Japanese Unexamined Patent Application Publication No. (hereinafter referred to as “Kokai”) H4-348143 discloses a composite silicone rubber powder obtained by coating the surface of a silicone rubber powder having an average particle size of 0.1 to 200 μm with a microfine metal oxide powder. Also Kokai H7-102075 discloses a composite silicone rubber powder composed of a silicone rubber powder having an average particle size of 0.1 to 200 μm and having density of silanol groups on the surface of no less than 2 per 100 Å2, the surface of the silicone rubber powder being coated with a microfine powder of amorphous silica having an average particle size not exceeding 1 μm. The aforementioned composite powders are obtained by mixing an aqueous dispersion of a silicone rubber powder with a metal oxide sol and then removing water from the obtained mixture (see Kokai H4-348143) or by adding a microfine powder of amorphous silica to an aqueous dispersion of a silicone rubber powder and then heating the product in order to remove water (see Kokai H7-102075).
Even though the composite silicone rubber powders could be readily obtained, they still demonstrate insufficient dispersibility in coating and cosmetic materials. It is also impossible to sufficiently improve matting properties in coating materials and to ensure comfortable feeling of use of cosmetic materials.
It is an object of the present invention to provide a composite silicone rubber powder characterized by excellent dispersibility in coating and cosmetic materials and having the possibility of improving matting properties of coating materials and feeling of use of cosmetic materials. It is another object to provide an efficient method of manufacturing the aforementioned composite silicone rubber powder. It is still another object to provide coating materials capable of forming coating films with excellent matting characteristics and cosmetic materials with improved feeling of use.